JP2005326794A - Optical scanning device and image forming apparatus - Google Patents

Optical scanning device and image forming apparatus Download PDF

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JP2005326794A
JP2005326794A JP2004149022A JP2004149022A JP2005326794A JP 2005326794 A JP2005326794 A JP 2005326794A JP 2004149022 A JP2004149022 A JP 2004149022A JP 2004149022 A JP2004149022 A JP 2004149022A JP 2005326794 A JP2005326794 A JP 2005326794A
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scanning
optical
optical system
scanning device
long lens
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Yasumasa Tomita
泰正 富田
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Ricoh Co Ltd
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Ricoh Co Ltd
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Priority to US10/992,692 priority patent/US7397589B2/en
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Priority to US12/120,919 priority patent/US20080225365A1/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/12—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using the sheet-feed movement or the medium-advance or the drum-rotation movement as the slow scanning component, e.g. arrangements for the main-scanning
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K15/00—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers
    • G06K15/02—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers
    • G06K15/12—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers by photographic printing, e.g. by laser printers
    • G06K15/129—Colour printing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/024—Details of scanning heads ; Means for illuminating the original
    • H04N1/028—Details of scanning heads ; Means for illuminating the original for picture information pick-up
    • H04N1/03—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a substantially linear array
    • H04N1/0301—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a substantially linear array using a bent optical path between the scanned line and the photodetector array, e.g. a folded optical path
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/12—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using the sheet-feed movement or the medium-advance or the drum-rotation movement as the slow scanning component, e.g. arrangements for the main-scanning
    • H04N1/121—Feeding arrangements
    • H04N1/122—Feeding arrangements using a feed belt
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/19—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using multi-element arrays
    • H04N1/191—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using multi-element arrays the array comprising a one-dimensional array, or a combination of one-dimensional arrays, or a substantially one-dimensional array, e.g. an array of staggered elements
    • H04N1/1911—Simultaneously or substantially simultaneously scanning picture elements on more than one main scanning line, e.g. scanning in swaths
    • H04N1/1916—Simultaneously or substantially simultaneously scanning picture elements on more than one main scanning line, e.g. scanning in swaths using an array of elements displaced from one another in the main scan direction, e.g. a diagonally arranged array
    • H04N1/1917—Staggered element array, e.g. arrays with elements arranged in a zigzag
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/19—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using multi-element arrays
    • H04N1/191—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using multi-element arrays the array comprising a one-dimensional array, or a combination of one-dimensional arrays, or a substantially one-dimensional array, e.g. an array of staggered elements
    • H04N1/1911—Simultaneously or substantially simultaneously scanning picture elements on more than one main scanning line, e.g. scanning in swaths
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
    • H04N2201/04—Scanning arrangements
    • H04N2201/047—Detection, control or error compensation of scanning velocity or position
    • H04N2201/04753—Control or error compensation of scanning position or velocity
    • H04N2201/04755—Control or error compensation of scanning position or velocity by controlling the position or movement of a scanning element or carriage, e.g. of a polygonal mirror, of a drive motor

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Mechanical Optical Scanning Systems (AREA)
  • Facsimile Scanning Arrangements (AREA)
  • Facsimile Heads (AREA)
  • Laser Beam Printer (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide an opposed type optical scanning device enabling a high quality image to be obtained with a simple configuration and at a low cost, and to provide an image forming apparatus using the device. <P>SOLUTION: The opposed scanning type optical scanning device includes a plurality of scanning optical systems respectively corresponding to an even number of photoconductors 4, arranged to be substantially symmetrical to each other with a sole polygon mirror 21 (a rotating deflecting device) as a symmetry center, the polygon mirror 21 being arranged substantially at a center in a single optical housing 20, and the opposed scanning type optical scanning device scans the even number of photoconductors 4 simultaneously in a exposure manner with optical beams through the lenses 22, 23 and a plurality of folding-back mirrors 24, 25, 26 of each scanning optical system which are arrange to be symmetry in the right and left direction with the above rotary deflecting means as a symmetry axis, wherein each of the scanning optical systems includes the at least one long lens 23 having power in a sub-scanning direction, and wherein in each of the symmetrically arranged scanning optical systems with the polygon mirror 21 as the symmetry center, a same number of the folding-back mirrors is arranged downstream of the long lens, and wherein the long lenses 23 are arranged to be reversed relative to each other in respective scanning planes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、カラーレーザープリンタやカラーデジタル複写機などの多色画像形成装置において、複数の感光体上に同時に露光走査可能な、対向走査型光走査装置に適用されるもので、斯かる光走査装置内における光学素子の配置に関するものである。   The present invention is applied to a counter-scanning optical scanning apparatus capable of simultaneously performing exposure scanning on a plurality of photoconductors in a multicolor image forming apparatus such as a color laser printer or a color digital copying machine. The present invention relates to the arrangement of optical elements in the apparatus.

特開２００２-１９６２７１号公報JP 2002-196271 A

画像形成装置は、感光体上に潜像を書き込むための光走査装置を備えている。近年、カラーレーザープリンタやカラーデジタル複写機などにおいて、その生産性を向上するために、複数の感光体上に同時に露光走査を可能とする方式が採られている。このように複数の感光体上に同時に露光走査を可能とする光走査装置においては、各感光体に対応する走査光学系をそれぞれ有するため、単純に感光体の数に比例して、各光学素子の数が必要となり、部品点数が必然的に増加してしまう。   The image forming apparatus includes an optical scanning device for writing a latent image on the photosensitive member. In recent years, in order to improve the productivity of color laser printers, color digital copying machines, and the like, a system that enables exposure scanning on a plurality of photosensitive members simultaneously has been adopted. In this way, the optical scanning device that enables simultaneous exposure scanning on a plurality of photoconductors has a scanning optical system corresponding to each photoconductor, so each optical element is simply proportional to the number of photoconductors. And the number of parts inevitably increases.

そこで、複数の感光体に同時に露光走査する方式として、単一の回転偏向手段によって左右両側に露光走査を行う、所謂、対向走査型光走査装置の技術が上記特許文献１にも記載されているように知られている。かかる対向走査型光走査装置では、通常、単一の光学ハウジング内に各々の感光体に上へ露光走査を行うため、それぞれ独立した複数、すなわち感光体と同数の走査光学系を有している。一方で、装置の省スペース化を実現するため、唯一の回転偏向手段が上下２段の反射面を備えるとともに、各段にそれぞれ独立した走査光学系を配置している。   Therefore, as a method of simultaneously performing exposure scanning on a plurality of photoconductors, a technique of a so-called counter scanning type optical scanning device in which exposure scanning is performed on both the left and right sides by a single rotating deflection unit is also described in Patent Document 1. As known. Such an opposed scanning type optical scanning device usually has a plurality of independent scanning optical systems, that is, the same number of scanning optical systems as the photosensitive members, in order to perform exposure scanning on each photosensitive member in a single optical housing. . On the other hand, in order to save the space of the apparatus, the only rotating deflection means has two upper and lower reflecting surfaces, and independent scanning optical systems are arranged at each stage.

走査光学系を構成する光学素子としては、走査レンズ、複数の折り返しミラー及び副走査方向にパワーを持つ長尺レンズ（トロイダルレンズ）であり、これら光学素子の配置状態や素子自身の性能は画像品質に大きな影響を与える。   The optical elements that make up the scanning optical system are a scanning lens, a plurality of folding mirrors, and a long lens (toroidal lens) having power in the sub-scanning direction. It has a big influence on.

例えば、複数の感光体に同時に露光走査可能な光走査装置においては、各感光体上に形成される走査線のずれ、（ここでは、走査線湾曲）を常に一定に揃えることが重要であり、走査線の幾何特性が均一でないことにより、各々の重ね合わせがずれてしまい、画像劣化を引き起こしてしまう。特に、カラー画像形成装置などにおいて、複数の感光体に各々別々の色のトナーを現像させる場合、各感光体上の色ずれにより、色再現性の劣化がきわめて顕著に生じてしまうこととなる。   For example, in an optical scanning device that can simultaneously scan and expose a plurality of photoconductors, it is important to always keep the shift of the scan lines formed on each photoconductor (here, the scan line curve) constant. Since the geometric characteristics of the scanning lines are not uniform, the respective overlays are deviated and image deterioration is caused. In particular, in a color image forming apparatus or the like, when developing different color toners on a plurality of photoconductors, the color reproducibility deteriorates remarkably due to the color shift on each photoconductor.

一般に、走査線の曲がりについては、走査光学系内部に具備した副走査方向にパワーを有する走査レンズ（＝通常は、長尺レンズに相当する）による影響が支配的である。すなわち、走査レンズの光軸中心を形成する焦線と、レンズの取り付け面（座面）が平行でない場合に、走査線曲がりが生じるが、この、焦線曲がりは、レンズ成型上、その加工限界から不可避の要因であり、仮に焦線曲がりを低減できたとしても加工上のコストアップに繋がる可能性がある。   In general, the bending of the scanning line is dominated by the effect of a scanning lens having power in the sub-scanning direction provided in the scanning optical system (usually corresponding to a long lens). That is, when the focal line forming the optical axis center of the scanning lens and the lens mounting surface (seat surface) are not parallel, scanning line bending occurs. This focal line bending is a processing limit in lens molding. Therefore, even if the bending of the focal line can be reduced, it may lead to an increase in processing cost.

特に、近年安価、且つ自由曲面を形成できるといったメリットから樹脂レンズが多く用いられているが、成型時の内部歪や、金型温度不均一性などにより、上記の焦線曲がりはガラスレンズのそれにくらべ、より顕著に生じてしまう。   In particular, resin lenses are often used in recent years because of their low cost and the ability to form free-form surfaces. However, due to internal distortion during molding and non-uniformity in mold temperature, the above-mentioned focal curve is similar to that of glass lenses. Compared to more prominent.

また、このような対向走査型光走査装置においては、各々の感光体上のビームスポット特性をすべて等しくすることも重要であり、僅かでも各々の感光体上のビーム特性が異なってしまうと、それによって、色再現性の劣化、色相ムラなどの画像不良を引き起こすことになってしまう。ここで言う「ビームスポット特性」とは、単にビームスポット径のみならず、ビーム強度（光量）や、ビームスポット位置（結像位置）も含まれ、各感光体上にいかに均一な露光を行うかが重要となってくる。ビームスポット特性の劣化を及ぼす原因としては、例えば、光走査装置における光学ハウジング内部の温度上昇に伴う、各光学素子の取り付け位置の熱膨張による変形、あるいは各光学素子に対するビームの入射位置のズレなどが挙げられる。   In such an opposed scanning type optical scanning device, it is also important to make all the beam spot characteristics on each photoconductor equal. If the beam characteristics on each photoconductor are slightly different, As a result, image defects such as deterioration of color reproducibility and hue unevenness are caused. The “beam spot characteristics” here includes not only the beam spot diameter but also the beam intensity (light quantity) and the beam spot position (imaging position), and how to perform uniform exposure on each photoconductor. Becomes important. Causes of the deterioration of the beam spot characteristics include, for example, deformation due to thermal expansion of the mounting position of each optical element due to temperature rise inside the optical housing in the optical scanning device, or deviation of the incident position of the beam on each optical element, etc. Is mentioned.

本発明は、かかる従来技術を解決するために、簡素な構成で且つ低コスト化を実現し、さらには高画像品質を可能とする、対向走査型光走査装置及び画像形成装置を提供することを目的とする。   In order to solve such a conventional technique, the present invention provides a counter-scanning optical scanning device and an image forming apparatus that achieve a low cost and a high image quality with a simple configuration. Objective.

上記目的を達成するために、本発明は、単一の光学ハウジング内の略中央に備えられた唯一の回転偏向手段を中心として略対称となるように配置され、偶数個の感光体に対応する複数の走査光学系を備え、各走査光学系の光学素子を介し、前記回転偏向手段を対称軸として左右に振り分けて、偶数個の感光体に同時に露光走査する対向走査型光走査装置であって、各走査光学系が光学素子としてそれぞれ複数の折り返しミラーと副走査方向にパワーを持つ少なくとも１枚の長尺レンズとを有し、前記回転偏向手段を中心に、互いに対称に配置される各走査光学系に対し、前記長尺レンズ以降の折り返しミラーの枚数を同数配置するとともに、長尺レンズが各々の走査面内において反転させて取り付けられていることを特徴としている。   In order to achieve the above object, the present invention is arranged so as to be substantially symmetric with respect to only one rotation deflecting means provided substantially at the center in a single optical housing, and corresponds to an even number of photoconductors. A counter-scanning optical scanning device comprising a plurality of scanning optical systems and performing exposure scanning on an even number of photosensitive members at the same time by distributing to the left and right with the rotational deflection means as a symmetry axis via optical elements of each scanning optical system. Each scanning optical system has a plurality of folding mirrors as optical elements and at least one long lens having power in the sub-scanning direction, and is arranged symmetrically with respect to the rotational deflection means. The optical system is characterized in that the same number of folding mirrors after the long lens are arranged, and the long lenses are mounted so as to be reversed in each scanning plane.

また、上記目的を達成するために、本発明は、単一の光学ハウジング内の略中央に備えられた唯一の回転偏向手段を中心として略対称となるように配置され、偶数個の感光体に対応する複数の走査光学系を備え、各走査光学系の光学素子を介し、前記回転偏向手段を対称軸として左右に振り分けて、偶数個の感光体に同時に露光走査する対向走査型光走査装置であって、各走査光学系が光学素子としてそれぞれ複数の折り返しミラーと副走査方向にパワーを持つ少なくとも１枚の長尺レンズとを有し、前記回転偏向手段を中心に、左右の一方の方向において近い位置と遠い位置に配置される各走査光学系に対し、長尺レンズが各々の走査面内において反転させて取り付けられているとともに、前記長尺レンズ以降の折り返しミラーの枚数の差が、２Ｎ−１（Ｎは自然数）となるように配置することを特徴としている。   In order to achieve the above object, the present invention is arranged so as to be substantially symmetric with respect to only one rotation deflecting means provided substantially at the center in a single optical housing, so that an even number of photoconductors are arranged. A counter-scanning optical scanning device that includes a plurality of corresponding scanning optical systems and distributes the rotation deflection means to the left and right with the rotational deflection means as the symmetry axis via the optical elements of each scanning optical system, and simultaneously exposes and scans even numbers of photoconductors. Each scanning optical system has a plurality of folding mirrors and at least one long lens having power in the sub-scanning direction as optical elements, and in one of the left and right directions centering on the rotating deflection means. For each scanning optical system arranged at a near position and a far position, a long lens is mounted in an inverted manner in each scanning plane, and the difference in the number of folding mirrors after the long lens. , 2N-1 (N is a natural number) is characterized by arranging such that.

なお、本発明は、前記長尺レンズが樹脂材料による成形品であると、効果的である。
さらにまた、上記目的を達成するために、本発明は、単一の光学ハウジング内の略中央に備えられた唯一の回転偏向手段を中心として略対称となるように配置され、偶数個の感光体に対応する複数の走査光学系を備え、各走査光学系の光学素子を介し、前記回転偏向手段を対称軸として左右に振り分けて、偶数個の感光体に同時に露光走査する対向走査型光走査装置であって、各走査光学系が光学素子としてそれぞれ複数の折り返しミラーと副走査方向にパワーを持つ少なくとも１枚の長尺レンズとを有し、回転偏向手段を中心に各々対称配置された各折り返しミラー間の距離を、回転偏向手段における反射部を含めて、互いに等しくすることを特徴としている。 The present invention is effective when the long lens is a molded product made of a resin material.
Furthermore, in order to achieve the above object, the present invention is arranged so as to be substantially symmetric with respect to only one rotating deflection means provided substantially at the center in a single optical housing, and an even number of photoreceptors. A counter scanning optical scanning device that includes a plurality of scanning optical systems corresponding to the above, and distributes the rotation deflecting means to the left and right around the optical element of each scanning optical system, and exposes and scans an even number of photosensitive members simultaneously. Each scanning optical system has a plurality of folding mirrors as optical elements and at least one long lens having power in the sub-scanning direction, and each folding is arranged symmetrically around the rotation deflecting means. The distance between the mirrors is equal to each other including the reflection portion in the rotating deflection unit.

なお、本発明は、回転偏向手段を中心に対称配置された折り返しミラー面での光線の成す角を、少なくとも一対で互いに等しくすると、効果的である。
さらに、本発明は、感光体表面上へ走査光を導く最終の折り返しミラーから感光体表面上までの距離を、各走査光学系に対し各々等しくすると、効果的である。
さらにまた、上記目的を達成するために、本発明は、単一の光学ハウジング内の略中央に備えられた唯一の回転偏向手段を中心として略対称となるように配置され、偶数個の感光体に対応する複数の走査光学系を備え、各走査光学系の光学素子を介し、前記回転偏向手段を対称軸として左右に振り分けて、偶数個の感光体に同時に露光走査する対向走査型光走査装置であって、各走査光学系が光学素子としてそれぞれ複数の折り返しミラーと副走査方向にパワーを持つ少なくとも１枚の長尺レンズとを有し、前記回転偏向手段を中心に、左右方向における遠い位置に配置される各走査光学系に対し、すべての前記折り返しミラーを前記走査レンズの下流側に配置したことを特徴としている。 The present invention is effective when the angles formed by the light beams on the folding mirror surfaces arranged symmetrically with respect to the rotating deflection means are equal to each other in at least one pair.
Further, the present invention is effective when the distance from the final folding mirror for guiding the scanning light onto the surface of the photosensitive member to the surface of the photosensitive member is made equal for each scanning optical system.
Furthermore, in order to achieve the above object, the present invention is arranged so as to be substantially symmetric with respect to only one rotating deflection means provided substantially at the center in a single optical housing, and an even number of photoreceptors. A counter scanning optical scanning device that includes a plurality of scanning optical systems corresponding to the above, and distributes the rotation deflecting means to the left and right around the optical element of each scanning optical system, and exposes and scans an even number of photosensitive members simultaneously. Each scanning optical system has a plurality of folding mirrors as optical elements and at least one long lens having power in the sub-scanning direction, and is located at a distant position in the left-right direction with the rotation deflecting unit as a center. All the folding mirrors are arranged on the downstream side of the scanning lens with respect to each scanning optical system.

なお、本発明は、前記回転偏向手段を中心に、左右方向における近い位置に配置される各走査光学系は前記走査レンズの手前に1枚の前記折り返しミラーを配置すると、効果的である。   In the present invention, it is effective that each of the scanning optical systems arranged at positions close to each other in the left-right direction with the rotation deflecting unit as the center is provided with one folding mirror in front of the scanning lens.

さらに、本発明は、前記走査レンズの手前に配置した折り返しミラーが他の折り返しミラーより短方向の幅が広いと、効果的である。
さらにまた、本発明は、各々の走査光学系を形成する折り返しミラーの数を、何れの走査光学系でも同じ数とすると、効果的である。 Furthermore, the present invention is effective when the folding mirror disposed in front of the scanning lens is wider in the short direction than the other folding mirrors.
Furthermore, the present invention is effective when the number of folding mirrors forming each scanning optical system is the same in any scanning optical system.

さらにまた、上記目的を達成するために、本発明は、請求項１〜１０のいずれか一項に記載の光走査装置を備えたことを特徴としている。   Furthermore, in order to achieve the above object, the present invention is characterized by including the optical scanning device according to any one of claims 1 to 10.

請求項１の構成によれば、単一の光学ハウジング内の略中央に備えられた唯一の回転偏向手段を中心として略対称となるように配置され、偶数個の感光体に対応する複数の走査光学系を備え、各走査光学系の光学素子を介し、前記回転偏向手段を対称軸として左右に振り分けて、偶数個の感光体に同時に露光走査する対向走査型光走査装置であって、各走査光学系が光学素子としてそれぞれ複数の折り返しミラーと副走査方向にパワーを持つ少なくとも１枚の長尺レンズとを有し、前記回転偏向手段を中心に、互いに対称に配置される各走査光学系に対し、前記長尺レンズ以降の折り返しミラーの枚数を同数配置するとともに、長尺レンズが各々の走査面内において反転させて取り付けられているので、回転偏向手段を中心に各々対称に配置される各走査光学系において、感光体面上への走査線曲がりの方向を揃えることができ、各感光体上の色ずれを抑えて高画像品質を保つことができる。   According to the first aspect of the present invention, a plurality of scans corresponding to an even number of photoconductors are arranged so as to be substantially symmetric with respect to a single rotational deflection means provided substantially at the center in a single optical housing. An opposed scanning optical scanning device that includes an optical system and that performs exposure scanning simultaneously on an even number of photosensitive members, with the rotational deflecting means being distributed to the left and right through the optical elements of each scanning optical system. Each optical system has a plurality of folding mirrors and at least one long lens having power in the sub-scanning direction as optical elements, and each scanning optical system arranged symmetrically with respect to the rotational deflection means. On the other hand, the same number of folding mirrors after the long lens are arranged, and the long lenses are mounted so as to be reversed in each scanning plane, so that they are arranged symmetrically around the rotation deflection means. In the scanning optical system, it is possible to align the direction of scanning line bending to the photoreceptor surface, it is possible to maintain the high image quality by suppressing the color shift on each photoconductor.

請求項２の構成によれば、単一の光学ハウジング内の略中央に備えられた唯一の回転偏向手段を中心として略対称となるように配置され、偶数個の感光体に対応する複数の走査光学系を備え、各走査光学系の光学素子を介し、前記回転偏向手段を対称軸として左右に振り分けて、偶数個の感光体に同時に露光走査する対向走査型光走査装置であって、各走査光学系が光学素子としてそれぞれ複数の折り返しミラーと副走査方向にパワーを持つ少なくとも１枚の長尺レンズとを有し、前記回転偏向手段を中心に、左右の一方の方向において近い位置と遠い位置に配置される各走査光学系に対し、長尺レンズが各々の走査面内において反転させて取り付けられているとともに、前記長尺レンズ以降の折り返しミラーの枚数の差が、２Ｎ−１（Ｎは自然数）となるように配置するので、全ての感光体面上の走査線曲がりの方向を揃えることが可能であり、全感光体上の色ずれを抑えて高画像品質を保つことができる。   According to the configuration of the second aspect, a plurality of scans corresponding to an even number of photoconductors are arranged so as to be substantially symmetric with respect to a single rotational deflection means provided substantially at the center in a single optical housing. An opposed scanning optical scanning device that includes an optical system and that performs exposure scanning simultaneously on an even number of photosensitive members, with the rotational deflecting means being distributed to the left and right through the optical elements of each scanning optical system. The optical system has a plurality of folding mirrors and at least one long lens having power in the sub-scanning direction as optical elements, respectively, and near and far positions in one of the left and right directions with the rotational deflection means as a center. Are attached to each scanning optical system in an inverted manner in each scanning plane, and the difference in the number of folding mirrors after the long lens is 2N-1 (N is Since arranged so as to be natural number), it is possible to align the direction of scanning line bending on all the photoreceptor surface, it is possible to maintain the high image quality by suppressing the color shift on the total photoreceptor.

請求項３の構成によれば、長尺レンズが樹脂材料による成形品であるので、成型時に生じる焦線曲がりが発生しても、上記の如くその影響を抑えることで、結果的に大幅なコストダウンが可能となる。   According to the third aspect of the present invention, since the long lens is a molded product made of a resin material, even if a focal line bending that occurs during molding occurs, the influence is suppressed as described above, resulting in a significant cost. Down is possible.

請求項４の構成によれば、単一の光学ハウジング内の略中央に備えられた唯一の回転偏向手段を中心として略対称となるように配置され、偶数個の感光体に対応する複数の走査光学系を備え、各走査光学系の光学素子を介し、前記回転偏向手段を対称軸として左右に振り分けて、偶数個の感光体に同時に露光走査する対向走査型光走査装置であって、各走査光学系が光学素子としてそれぞれ複数の折り返しミラーと副走査方向にパワーを持つ少なくとも１枚の長尺レンズとを有し、回転偏向手段を中心に各々対称配置された各折り返しミラー間の距離を、回転偏向手段における反射部を含めて、互いに等しくするので、各ミラーの走査幅をそれぞれ等しくすることができ、部品の共通化によるコストダウンが可能である。   According to the configuration of the fourth aspect, a plurality of scans corresponding to an even number of photoconductors are arranged so as to be substantially symmetric with respect to a single rotational deflection means provided at a substantially central position in a single optical housing. An opposed scanning optical scanning device that includes an optical system, and performs exposure scanning simultaneously on an even number of photosensitive members, with the rotational deflecting means being distributed to the left and right through the optical elements of each scanning optical system. The optical system has a plurality of folding mirrors as optical elements and at least one long lens having power in the sub-scanning direction, and the distance between the folding mirrors that are symmetrically arranged around the rotation deflecting means. Since the reflecting portions of the rotating deflection means are made equal to each other, the scanning widths of the mirrors can be made equal, and the cost can be reduced by sharing the parts.

請求項５の構成によれば、回転偏向手段を中心に対称配置された折り返しミラー面での光線の成す角を、少なくとも一対で互いに等しくしたので、各ミラーの反射率を等しくすることができ、ミラー毎にコーティング条件を異ならせる必要がなくなり、コストダウンが可能である。   According to the configuration of claim 5, since the angles formed by the light beams on the folding mirror surfaces symmetrically arranged around the rotation deflecting means are equal to each other in at least a pair, the reflectivity of each mirror can be made equal. It is not necessary to change the coating conditions for each mirror, and the cost can be reduced.

請求項６の構成によれば、感光体表面上へ走査光を導く最終の折り返しミラーから感光体表面上までの距離を、各走査光学系に対し各々等しくしたので、部品の共通化によるコストダウンが可能である。   According to the configuration of the sixth aspect, the distance from the final folding mirror that guides the scanning light onto the surface of the photosensitive member to the surface of the photosensitive member is made equal for each scanning optical system. Is possible.

請求項６の構成によれば、単一の光学ハウジング内の略中央に備えられた唯一の回転偏向手段を中心として略対称となるように配置され、偶数個の感光体に対応する複数の走査光学系を備え、各走査光学系の光学素子を介し、前記回転偏向手段を対称軸として左右に振り分けて、偶数個の感光体に同時に露光走査する対向走査型光走査装置であって、各走査光学系が光学素子としてそれぞれ複数の折り返しミラーと副走査方向にパワーを持つ少なくとも１枚の長尺レンズとを有し、前記回転偏向手段を中心に、左右方向における遠い位置に配置される各走査光学系に対し、すべての前記折り返しミラーを前記走査レンズの下流側に配置したので、折り返しミラーの取り付け位置の変動等による与えるビームスポット特性の悪影響を防止して高画像品質を保つことができる。   According to the configuration of the sixth aspect, a plurality of scans corresponding to an even number of photoconductors are arranged so as to be substantially symmetric with respect to a single rotational deflection means provided substantially at the center in a single optical housing. An opposed scanning optical scanning device that includes an optical system, and performs exposure scanning simultaneously on an even number of photosensitive members, with the rotational deflecting means being distributed to the left and right through the optical elements of each scanning optical system. Each scanning optical system has a plurality of folding mirrors as optical elements and at least one long lens having power in the sub-scanning direction, and is arranged at a distant position in the left-right direction with the rotation deflecting unit as a center. Since all the folding mirrors are arranged on the downstream side of the scanning lens with respect to the optical system, the adverse effect of the beam spot characteristics caused by fluctuations in the mounting position of the folding mirrors can be prevented. It is possible to maintain the image quality.

請求項８の構成によれば、内側の感光体用走査光学系は光ビーム照射方向において走査レンズの手前に１枚の折り返しミラーを配置しているで、折り返しミラーの取り付け位置の変動等による与えるビームスポット特性の悪影響を低減して高画像品質を保つことができる。   According to the configuration of the eighth aspect, the inner scanning optical system for the photoconductor is provided with one folding mirror in front of the scanning lens in the light beam irradiation direction. High image quality can be maintained by reducing the adverse effect of beam spot characteristics.

請求項９の構成によれば、走査レンズの手前に配置１枚の折り返しミラーが他の１枚の折り返しミラーより短方向の幅を広いので、ミラー受け面の整列度を高精度にすることができ、ミラー倒れ等による光ビーム入射位置のバラツキを低減し、ビームスポット特性の悪影響を最小限に抑えて高画像品質を保つことができる。   According to the configuration of the ninth aspect, since one folding mirror disposed in front of the scanning lens is wider in the short direction than the other folding mirror, the alignment degree of the mirror receiving surface can be made high accuracy. It is possible to reduce the variation of the light beam incident position due to mirror tilting, etc., and to minimize the adverse effect of the beam spot characteristics and to maintain high image quality.

請求項１０の構成によれば、各々の走査光学系を形成する折り返しミラーの数を、何れの走査光学系でも同じ数とするので、各走査光学系における折り返しミラーの反射率の積上げによるばらつきを最小限に抑えることができ、各感光体表面上のビーム強度（光量）、及び各感光体表面上における走査線内のビーム強度偏差（シェーディング）について、各色ごとの差を抑えることができ、結果的に各色間の濃度ムラ，色相ムラの劣化を防ぐことが可能となる。   According to the configuration of the tenth aspect, since the number of the folding mirrors forming each scanning optical system is the same in any scanning optical system, variation due to an increase in the reflectance of the folding mirror in each scanning optical system is caused. As a result, the difference in each color can be suppressed with respect to the beam intensity (light intensity) on each photoconductor surface and the beam intensity deviation (shading) in the scanning line on each photoconductor surface. In particular, it is possible to prevent deterioration of density unevenness and hue unevenness between colors.

請求項１１の構成によれば、上記効果が得られる画像形成装置を提供することができる。   According to the configuration of the eleventh aspect, it is possible to provide an image forming apparatus that can obtain the above-described effect.

以下、本発明の実施の形態を添付図面にしたがって説明する。
図１は、画像形成装置の一例であるカラープリンタを示す概略図である。ここに示した画像形成装置は、像担持体としての中間転写ベルト１が配置され、中間転写ベルト１はローラ２，３に巻き掛けられ、その一方のローラが駆動ローラとして反時計方向に回転駆動することにより矢印Ａ方向に走行駆動される。また、中間転写ベルト１の下部走行辺には第１ないし第４のドラム状の感光体４Ｙ，４Ｃ，４Ｍ，４Ｂｋが並列配置され、この各感光体上にイエロートナー像、シアントナー像、マゼンタトナー像及びブラックトナー像がそれぞれ形成される。 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic diagram illustrating a color printer which is an example of an image forming apparatus. In the image forming apparatus shown here, an intermediate transfer belt 1 as an image carrier is disposed. The intermediate transfer belt 1 is wound around rollers 2 and 3, and one of the rollers is driven to rotate counterclockwise as a drive roller. As a result, the vehicle is driven in the direction of arrow A. Further, first to fourth drum-shaped photoconductors 4Y, 4C, 4M, and 4Bk are arranged in parallel on the lower running side of the intermediate transfer belt 1, and a yellow toner image, a cyan toner image, and a magenta are arranged on each photoconductor. A toner image and a black toner image are respectively formed.

この感光体４は図１における時計方向に回転駆動され、このとき図示していない帯電手段によって表面が所定の極性に均一に帯電され、その帯電面に光走査装置５から出射する光変調されたビームが照射される。これによって感光体４上に静電潜像が形成され、その静電潜像が現像装置（図示せず）によって例えば左端の感光体４Ｙではイエロートナー像として可視像化される。   The photosensitive member 4 is driven to rotate in the clockwise direction in FIG. 1. At this time, the surface is uniformly charged to a predetermined polarity by a charging means (not shown), and the charged surface is light-modulated to be emitted from the optical scanning device 5. A beam is irradiated. As a result, an electrostatic latent image is formed on the photoreceptor 4, and the electrostatic latent image is visualized as a yellow toner image on the photoreceptor 4Y at the left end, for example, by a developing device (not shown).

このようにして形成されたイエロートナー像は、感光体４Ｙと中間転写ベルト１を挟んで配置された転写ローラ６にトナーと逆極性の電圧が印加され、これによって感光体４Ｙ上のイエロートナー像が中間転写ベルト１上に転写される。全く同様にして、他の感光体４Ｃ，４Ｍ，４Ｂｋ上にシアントナー像、マゼンタトナー像及びブラックトナー像がそれぞれ形成され、これらのトナー像がイエロートナー像の転写された中間転写ベルト１上に順次重ね合されて転写される。このようにして中間転写ベルト１上に形成された４色からなるトナー像はベルト走行に伴って図１の右端の２次転写ローラ７が設けられた２次転写部へ移動する。   The yellow toner image thus formed is applied with a voltage having a polarity opposite to that of the toner to the transfer roller 6 disposed with the photoreceptor 4Y and the intermediate transfer belt 1 interposed therebetween, whereby the yellow toner image on the photoreceptor 4Y. Is transferred onto the intermediate transfer belt 1. In exactly the same manner, a cyan toner image, a magenta toner image, and a black toner image are formed on the other photoconductors 4C, 4M, and 4Bk, respectively, and these toner images are transferred onto the intermediate transfer belt 1 on which the yellow toner image is transferred. Sequentially superimposed and transferred. Thus, the four color toner images formed on the intermediate transfer belt 1 move to the secondary transfer portion provided with the secondary transfer roller 7 at the right end of FIG. 1 as the belt travels.

一方、装置本体の下部には給紙部８が設けられ、該給紙部８から給紙手段９によって例えば転写紙より成る記録材Ｐが矢印方向に給送される。給紙された記録材Ｐは，レジストローラ１０に突き当てられた後，記録材Ｐに正しくトナー像が転写されるタイミングで中間転写ベルト１の２次転写部へ送り込まれる。そして，２次転写ローラ７に対し中間転写ベルト１上のトナーと逆極性の電圧が印加され、これによって中間転写ベルト１上に重ね転写されたトナー像が記録材Ｐ上に転写される。トナー像が転写された記録材Ｐは、上方へ搬送されて定着装置１１を通過し、トナー像が定着された後、排紙ローラ１２を介して装置本体上面の排紙部に排出される。なお、転写後の感光体や中間転写ベルト１に残留するトナー等の汚れはそれぞれ図示していないクリーニング手段によって除去される。   On the other hand, a paper feed unit 8 is provided at the lower part of the apparatus main body, and a recording material P made of transfer paper, for example, is fed in the direction of the arrow from the paper feed unit 8 by a paper feed unit 9. The fed recording material P is abutted against the registration roller 10 and then sent to the secondary transfer portion of the intermediate transfer belt 1 at a timing at which the toner image is correctly transferred onto the recording material P. A voltage having a polarity opposite to that of the toner on the intermediate transfer belt 1 is applied to the secondary transfer roller 7, whereby the toner image superimposed and transferred onto the intermediate transfer belt 1 is transferred onto the recording material P. The recording material P to which the toner image has been transferred is conveyed upward and passes through the fixing device 11, and after the toner image is fixed, the recording material P is discharged to a paper discharge portion on the upper surface of the apparatus main body via a paper discharge roller 12. Note that dirt such as toner remaining on the photoreceptor after transfer and the intermediate transfer belt 1 is removed by cleaning means (not shown).

図２は、本発明に係る光走査装置を示す断面説明図である。図２において、光走査装置５は、２段式回転偏向手段（ポリゴンミラー／モータ）２１、走査レンズとしてのｆθレンズ２２、折り返しミラー（第１〜第３ミラー群）２４、２５、２６、長尺レンズ２３等を備えており、これらが光学ハウジング２０内に配設されている。ポリゴンミラー２１は、正多角形の側面に反射ミラーを有しており、モータ（図示せず）により高速回転され、不図示の光源からのレーザ光を偏向・走査する。ｆθレンズ２２は、ポリゴンミラー１によるビーム走査の等角度運動を等速直線運動へと変える光学素子である。第１〜第３ミラー群２４〜２６は、光走査装置５の上方に配置された各感光体４へとレーザ光を導く光学素子である。長尺レンズ２３はポリゴンミラーの面倒れを補正するもので、走査線の位置を副走査方向に補正する機能をもっている。   FIG. 2 is an explanatory sectional view showing an optical scanning device according to the present invention. In FIG. 2, the optical scanning device 5 includes a two-stage rotational deflection means (polygon mirror / motor) 21, an fθ lens 22 as a scanning lens, folding mirrors (first to third mirror groups) 24, 25, 26, and a length. A scale lens 23 and the like are provided, and these are arranged in the optical housing 20. The polygon mirror 21 has a reflection mirror on the side of a regular polygon, is rotated at high speed by a motor (not shown), and deflects and scans laser light from a light source (not shown). The fθ lens 22 is an optical element that changes the equiangular motion of the beam scanning by the polygon mirror 1 into a uniform linear motion. The first to third mirror groups 24 to 26 are optical elements that guide the laser light to the respective photosensitive members 4 disposed above the optical scanning device 5. The long lens 23 corrects the tilting of the polygon mirror and has a function of correcting the position of the scanning line in the sub-scanning direction.

ポリゴンミラー２１によって偏向走査された光束は、ｆθレンズ２２、折り返しミラー２４、２５、２６及び長尺レンズ２３の光学素子を経て、感光体４の表面上に露光される。ここで、各感光体４を、図２の右側から、黒（BK），マゼンタ（Ｍ），シアン（Ｃ），イエロー（Ｙ）の各色に対応するものとする。   The light beam deflected and scanned by the polygon mirror 21 is exposed on the surface of the photoconductor 4 through the optical elements of the fθ lens 22, the folding mirrors 24, 25 and 26, and the long lens 23. Here, it is assumed that each photoconductor 4 corresponds to each color of black (BK), magenta (M), cyan (C), and yellow (Y) from the right side of FIG.

各走査光学系は、図２に示すように、ポリゴンミラー２１を中心として左右に２組ずつ配置され、右側に黒、マゼンタ、左側にシアン、イエローが位置し、ポリゴンミラー２１を中心として内側、すなわちポリゴンミラー２１に近い側にマゼンタ、シアン、外側である遠い側に黒、イエローが位置している。そして、内側同士のマゼンタ走査光学系とシアン走査光学系、外側同士の黒走査光学系とイエロー走査光学系は互いに対称となるように配置されている。   As shown in FIG. 2, each scanning optical system is arranged in two sets on the left and right sides with the polygon mirror 21 as the center, black and magenta on the right side, cyan and yellow on the left side, and inside with the polygon mirror 21 as the center, That is, magenta and cyan are located on the side close to the polygon mirror 21, and black and yellow are located on the far side which is the outside. The inner magenta scanning optical system and cyan scanning optical system, and the outer black scanning optical system and yellow scanning optical system are arranged symmetrically with each other.

内側同士及び外側同士の各走査光学系は、ｆθレンズ２２、折り返しミラー２４、２５、２６及び長尺レンズ２３は、ポリゴンミラー２１から等距離となるように位置している。折り返しミラーは、ポリゴンミラー２１から、感光体４面上に至るまで各色３枚ずつ配置されている（第１ミラー２４、第２ミラー２５、第３ミラー２６）。   In each of the inner and outer scanning optical systems, the fθ lens 22, the folding mirrors 24, 25 and 26, and the long lens 23 are positioned so as to be equidistant from the polygon mirror 21. Three folding mirrors are arranged for each color from the polygon mirror 21 to the surface of the photoreceptor 4 (first mirror 24, second mirror 25, and third mirror 26).

長尺レンズ２３は、副走査方向により大きなパワーを有し、樹脂材料により成型されているものであり、図３に示すように、取り付け座面Ａに対し、上に凸の焦線曲がりＦを有する場合を想定する。該長尺レンズ２３は、走査面内に対し、上下両側に取り付け座面を有するものであり、各走査光学系に対し、任意に反転させて配置可能である。したがって、取り付け座面Ｂでは下に凸の焦線曲がりＦを有する。   The long lens 23 has a greater power in the sub-scanning direction and is molded of a resin material. As shown in FIG. 3, the long lens 23 has an upward convex focal line curve F with respect to the mounting seat surface A. Suppose you have one. The long lens 23 has mounting seat surfaces on both the upper and lower sides with respect to the scanning plane, and can be arbitrarily inverted with respect to each scanning optical system. Therefore, the mounting seat surface B has a downward convex focal line curve F.

このような焦線曲がりＦがあるとき、例えば、ポリゴンミラー２１を中心として、内側に配置されるマゼンダ，シアンのステーションに関して述べると、図４及び図５に示すように、マゼンダのステーションについては、取り付け座面Ａを下側、一方、シアンのステーションについては、反対側の取り付け座面Ｂを下側（座面Ａが上側）となるように配置し、さらに、長尺レンズ以降の折り返しミラー枚数を同数（この場合、マゼンダ，シアンの各ステーションにおいては、２枚となる）となるよう配置することにより、感光体上の走査線湾曲の方向はいずれも下に凸の形状を得ることができる。これによってマゼンダ，シアンの各色での走査線のずれを揃えることができる。なお、図４において長尺レンズ２３の断面において幅の長い方が座面Ａを示している。   When there is such a focal line curve F, for example, with respect to the magenta and cyan stations arranged inside with the polygon mirror 21 as the center, as shown in FIG. 4 and FIG. For the cyan station, the mounting seat surface A is on the lower side, and the opposite mounting seat surface B is on the lower side (the seat surface A is on the upper side). Are arranged in the same number (in this case, there are two in each of the magenta and cyan stations), so that the scanning line curve direction on the photosensitive member can have a downwardly convex shape. . This makes it possible to align the scan line shifts in magenta and cyan colors. In FIG. 4, the longer one in the cross section of the long lens 23 indicates the seating surface A.

同様に、ポリゴンミラー２１を中心として、外側に配置される黒，イエローの各ステーションに関しても、全く同じことが言える。すなわち、ポリゴンミラー２１を中心に、互いに対称に配設される各走査光学系に対し、長尺レンズ２３を各々の走査面内において反転して取り付け、長尺レンズ以降の折り返しミラー枚数を同数することによって、各走査光学系に対する感光体面上への走査線曲がりの方向をそろえることが可能であり、ビームスポット位置のズレ、つまるところの色ずれを低減することが可能である。   Similarly, the same can be said for the black and yellow stations arranged outside the polygon mirror 21 as the center. That is, with respect to each scanning optical system arranged symmetrically with respect to the polygon mirror 21, the long lens 23 is reversed and attached in each scanning plane, and the number of folding mirrors after the long lens is the same. As a result, it is possible to align the direction of scanning line bending on the photoreceptor surface with respect to each scanning optical system, and it is possible to reduce misalignment of beam spot positions and clogging color misregistration.

次に、ポリゴンミラー２１を中心にそれぞれ右側同士と左側同士の走査光学系に対しては、長尺レンズ２３が走査面内において各々反転させて取り付けられるとともに、長尺レンズ２３より以降の折り返しミラーの枚数の差が、２Ｎ−１（Ｎは自然数）となるように選択されている。   Next, with respect to the scanning optical systems on the right side and the left side with respect to the polygon mirror 21, the long lens 23 is mounted in an inverted manner in the scanning plane, and the folding mirror subsequent to the long lens 23 is attached. Is selected to be 2N-1 (N is a natural number).

すなわち、図４に示すように、内側右のマゼンダのステーションについては取り付け座面Ａを下側，内側左のシアンのステーションについては、反対側の取り付け座面Ｂを下側となるよう配置し、各々の長尺レンズ以降の折り返しミラー枚数を２枚と据えている。これに対して、外側右の黒のステーションについては、マゼンダのステーションに対し長尺レンズ２３を反転させて（図では、座面Ｂ側を取り付け面として選択）配置する。これは黒のステーションとマゼンダのステーションにおいて、ｆθレンズ２２と長尺レンズ２３間に折り返しミラーの有無に起因するものである。同様に、外側左のイエローのステーションについてはシアンのステーションに対して反転させて（図では、座面Ａを取り付け面として選択）配置しているとともに、長尺レンズ２３以降の折り返しミラーの枚数をそれぞれ３枚（３−２＝１・・・奇数）となるように選択している。なお、図４のイエローステーションとシアンステーションにおいて、イエローでは長尺レンズ２３Ｙの座面Ｂが下を向いており、また、シアンステーションでは座面Ｂが右下を向いているが、シアンステーションは折り返しミラー２４Ｃで反転しており、このときのイエローステーションとシアンステーションは長尺レンズ２３が互いに反転されて配置されていることになる。   That is, as shown in FIG. 4, the mounting seat surface A is positioned on the lower side for the inner right magenta station, and the mounting seat surface B on the opposite side is positioned on the lower side for the inner left cyan station. The number of folding mirrors after each long lens is set to two. On the other hand, for the black station on the outer right, the long lens 23 is inverted with respect to the magenta station (in the figure, the seating surface B side is selected as the mounting surface) and arranged. This is due to the presence or absence of a folding mirror between the fθ lens 22 and the long lens 23 in the black station and the magenta station. Similarly, the outer left yellow station is reversed with respect to the cyan station (the seat surface A is selected as the attachment surface in the figure), and the number of folding mirrors after the long lens 23 is set. Each of them is selected to be 3 (3-2 = 1... Odd number). In the yellow station and cyan station in FIG. 4, in yellow, the seating surface B of the long lens 23Y faces downward, and in the cyan station, the seating surface B faces lower right, but the cyan station turns back. The yellow lens and the cyan station are inverted by the mirror 24C, and the long lenses 23 are inverted from each other.

この構成を備えることにより、黒，マゼンダ，シアン，イエロー各色における感光体上の走査線湾曲の方向は、全て下に凸の形状を得ることができ、全色で走査線のずれをそろえることができる。   With this configuration, the scanning line curve direction on the photosensitive member in each of the colors black, magenta, cyan, and yellow can be convex downward, and the scanning lines can be aligned for all colors. it can.

その結果、全ての感光体に対応する走査光学系の走査線曲がりの方向をそろえることが可能であり、ビームスポット位置のズレ、つまるところの色ずれを低減することが可能である。   As a result, it is possible to align the scanning line bending direction of the scanning optical system corresponding to all the photoconductors, and it is possible to reduce the deviation of the beam spot position and the color misregistration.

さらに、本光走査装置５は図２に示すように、ポリゴンミラー２１を中心として、各走査光学系の走査レンズ（ｆθレンズ２２、長尺レンズ２３）及び折り返しミラー２４、２５、２６が左右に振り分けられ、各ミラー間の距離がポリゴンミラー２１における反射部を含めて等しくなっている。例えば、ポリゴンミラー２１を中心として内側に配されたマゼンタ走査光学系、シアン走査光学系においては、ポリゴンミラー２１における反射点から第１ミラー２４までの距離（ｅ＝ｉ）、第１ミラー２４から第２ミラー２５までの距離（ｆ＝ｊ）、第２ミラー２５から第３ミラー２６までの距離（ｇ＝ｋ）を各色で互いに等しくしている。要するに、ポリゴンミラー反射点を含め、各ミラー間の距離が各々等距離であって、このために、対称配置となる各ミラーの走査幅を等しくできる。つまり、マゼンタ，シアンの各走査光学系に対し、第１ミラー２４、第２ミラー２５、第３ミラー２６を各々共通とすることが可能である。同様に、外側に位置するブラック、イエローの各色に対応する走査光学系での折り返しミラーにおいても、全く同じことが当てはまる
（ａ＝ｍ、ｂ＝ｎ、ｃ＝ｏ）。 Further, as shown in FIG. 2, the optical scanning device 5 has a scanning lens (fθ lens 22 and long lens 23) and folding mirrors 24, 25, and 26 of each scanning optical system in the horizontal direction with the polygon mirror 21 as the center. The distances between the mirrors are the same including the reflection part of the polygon mirror 21. For example, in a magenta scanning optical system and a cyan scanning optical system arranged on the inner side with respect to the polygon mirror 21, the distance (e = i) from the reflection point on the polygon mirror 21 to the first mirror 24, and from the first mirror 24. The distance from the second mirror 25 (f = j) and the distance from the second mirror 25 to the third mirror 26 (g = k) are the same for each color. In short, the distances between the mirrors including the polygon mirror reflection point are equal to each other. For this reason, the scanning widths of the mirrors arranged symmetrically can be made equal. That is, the first mirror 24, the second mirror 25, and the third mirror 26 can be made common to the magenta and cyan scanning optical systems. Similarly, the same applies to the folding mirror in the scanning optical system corresponding to each of black and yellow colors located outside (a = m, b = n, c = o).

本例における光走査装置５については、計１２枚の折り返しミラーを有しているが、少なくとも６組の折り返しミラーはその長手方向の長さにおいて互いに共通化可能となる。   The optical scanning device 5 in this example has a total of 12 folding mirrors, but at least 6 pairs of folding mirrors can be shared with each other in the length in the longitudinal direction.

また、上記各走査光学系に対して、ポリゴンミラー２１を中心に、各々対称的に配置された各ミラー面での光線の成す角は、互いに等しい。例えば、マゼンタ，シアンの各色に対応する走査光学系において、第１ミラー２４、第２ミラー２５の入射光線と反射光線で成す角を互いに等しく（γ＝ε、δ＝ζ）し、各ミラー面での反射率を同一にすることで、ミラー毎にコーティング条件を替える必要がなくなる。同様に、外側に位置するブラック、イエローの各色に対応する走査光学系での折り返しミラーにおいても、全く同じことが当てはまる（α＝η、β＝θ）。   In addition, the angles formed by the light beams on the mirror surfaces that are symmetrically arranged around the polygon mirror 21 with respect to each scanning optical system are equal to each other. For example, in the scanning optical system corresponding to each color of magenta and cyan, the angles formed by the incident light and the reflected light of the first mirror 24 and the second mirror 25 are equal to each other (γ = ε, δ = ζ), and each mirror surface By making the reflectance at the same, there is no need to change the coating conditions for each mirror. Similarly, the same applies to the folding mirror in the scanning optical system corresponding to each of black and yellow colors located outside (α = η, β = θ).

つまり、以上の構成においては、対称配置となる各折り返しミラーの長さや反射率の何れも全く同じ部品を使用することが可能である。
さらに、感光体表面上へ走査光を導く最終ミラーから感光体表面までの距離が、全ての走査光学系において各々等しい。つまり、ブラック、マゼンタ、シアン、イエローにおける第３ミラー２６から感光体４表面までが全て等距離である（ｄ＝ｈ＝ｌ＝ｐ）。これによって、最終ミラーの走査幅を各色全てで等しくすることができ、全ての第３ミラー２６を共通化することが可能である。 That is, in the above configuration, it is possible to use parts having the same length and reflectance of each folding mirror that is symmetrically arranged.
Further, the distance from the final mirror that guides the scanning light onto the surface of the photosensitive member to the surface of the photosensitive member is equal in all the scanning optical systems. That is, the distance from the third mirror 26 to the surface of the photoconductor 4 in black, magenta, cyan, and yellow is all equal (d = h = l = p). Thereby, the scanning width of the final mirror can be made equal for all the colors, and all the third mirrors 26 can be shared.

そして、各々の走査光学系を形成する折り返しミラーの数は、何れの走査光学系においても同じ数だけ存する構成となっている（本例の場合、各走査光学系において３個のミラー）。このような構成により、各走査光学系における折り返しミラーの反射率の積上げによるばらつきを最小限に抑えることができ、各感光体表面上のビーム強度（光量）、及び各感光体表面上における走査線内のビーム強度偏差（シェーディング）について、各色ごとの差を抑えることができ、結果的に各色間の濃度ムラ、色相ムラの劣化を防ぐことが可能となる。   The number of folding mirrors forming each scanning optical system is the same in any scanning optical system (in this example, three mirrors in each scanning optical system). With such a configuration, it is possible to minimize the variation due to accumulation of the reflectivity of the folding mirror in each scanning optical system, the beam intensity (light quantity) on each photoreceptor surface, and the scanning line on each photoreceptor surface. With respect to the beam intensity deviation (shading), it is possible to suppress the difference for each color, and as a result, it is possible to prevent deterioration of density unevenness and hue unevenness between colors.

また、上記構成の光走査装置は外側のブラック、イエロー走査光学系は折り返しミラー２４，２５，２６の下流側にｆθレンズ２２を配置していない、すなわちｆθレンズ２２の手前に折り返しミラーを配置しないように構成している。かかる構成により外側の走査光学系は折り返しミラーを介してｆθレンズ２２に入射することがないので、折り返しミラーの取り付け位置の変動による影響を皆無にすることができる。したがって、ｆθレンズ２２へのビームの入射位置のバラツキを抑えることができ、ビームスポット特性の劣化を防ぐことができる。   Further, in the optical scanning device having the above configuration, the outer black and yellow scanning optical systems do not arrange the fθ lens 22 downstream of the folding mirrors 24, 25, 26, that is, do not arrange the folding mirror in front of the fθ lens 22. It is configured as follows. With this configuration, the outer scanning optical system does not enter the fθ lens 22 via the folding mirror, so that it is possible to eliminate the influence of fluctuations in the mounting position of the folding mirror. Therefore, variation in the incident position of the beam on the fθ lens 22 can be suppressed, and deterioration of the beam spot characteristics can be prevented.

また、光走査装置はマゼンタ、シアンの内側の走査光学系においてｆθレンズ２２の手前に折り返しミラーを１枚のみ配置している。かかる構成により内側感光体４に照射するビームは1枚の折り返しミラー２４を介してｆθレンズ２２に入射するので、折り返しミラー２４の取り付け位置の変動による影響を最小限にすることができる。したがって、ｆθレンズ２２へのビームの入射位置のバラツキを減らして、ビームスポット特性の劣化を軽減することができる。   In the optical scanning device, only one folding mirror is arranged in front of the fθ lens 22 in the scanning optical system inside magenta and cyan. With this configuration, the beam irradiated on the inner photoconductor 4 is incident on the fθ lens 22 via the single folding mirror 24, so that the influence of fluctuations in the mounting position of the folding mirror 24 can be minimized. Therefore, variations in the incident position of the beam on the fθ lens 22 can be reduced, and deterioration of the beam spot characteristics can be reduced.

ところで、内側の走査光学系はｆθレンズ２２の手前に折り返しミラー２４を１枚のみ配置しているので、ｆθレンズ２２の手前に折り返しミラーを配置しない外側の走査光学系と比べると、ビームスポット特性の劣化がある。そこで、内側の走査光学系はビーム照射方向においてｆθレンズ２２の手前に第１折り返しミラー２４を他のミラーと比べて短方向の幅が広いものを用いる。なお、折り返しミラー２４は図２の紙面と直交する方向が長手方向で表示される幅が短方向である。   By the way, since the inner scanning optical system has only one folding mirror 24 disposed in front of the fθ lens 22, compared with the outer scanning optical system in which no folding mirror is disposed in front of the fθ lens 22, the beam spot characteristics. There is deterioration. Therefore, the inner scanning optical system uses a first folding mirror 24 that is wider in the short direction than the other mirrors in front of the fθ lens 22 in the beam irradiation direction. The folding mirror 24 has a short width in which the direction perpendicular to the paper surface of FIG.

このようにｆθレンズ２２の手前に配置した折り返しミラー２４に短方向の幅が広いミラーを用いることで、ミラー受け面の整列度をより高精度にすることができ、ミラーの倒れ等によるビームの入射位置のバラツキをより抑えることができる。   By using a mirror having a wide width in the short direction as the folding mirror 24 arranged in front of the fθ lens 22 in this way, the degree of alignment of the mirror receiving surface can be made higher, and the beam caused by mirror tilting or the like can be obtained. Variation in incident position can be further suppressed.

以上、本発明の好ましい実施形態について説明したが、本発明は上記実施形態に限定されず、各種改変できるものである。例えば、画像形成装置は各作像ユニットに形成したトナー像を中間転写ベルトに重ね転写し、その後一括で記録材に転写しているが、搬送ベルトに搬送される記録材に各作像ユニットに形成したトナー像を順次重ね転写する形式のタンデム式画像形成装置にも適用できる。   As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to the said embodiment, Various modifications can be made. For example, the image forming apparatus superimposes and transfers the toner image formed on each image forming unit onto the intermediate transfer belt, and then transfers the toner image to the recording material all at once. The present invention can also be applied to a tandem image forming apparatus in which the formed toner images are sequentially superimposed and transferred.

本発明に係る光走査装置の一例を備えた画像形成装置の概略を示す断面構成図である。1 is a cross-sectional configuration diagram illustrating an outline of an image forming apparatus including an example of an optical scanning device according to the present invention. 本発明の一実施例に係る光走査装置の、副走査方向における断面構成図である。1 is a cross-sectional configuration diagram of an optical scanning device according to an embodiment of the present invention in a sub-scanning direction. 本発明の長尺レンズを示し、（ａ）は斜視図、（ｂ）は説明図、（ｃ）は正面図である。The long lens of this invention is shown, (a) is a perspective view, (b) is explanatory drawing, (c) is a front view. 本発明に係る光走査装置の長尺レンズ配置状態と焦線曲がりの関係を示す説明図である。It is explanatory drawing which shows the relationship between the elongate lens arrangement | positioning state and focal line bending of the optical scanner which concerns on this invention. 本発明に係る光走査装置の長尺レンズ配置状態を示す斜視説明図である。It is a perspective explanatory view showing a long lens arrangement state of the optical scanning device according to the present invention.

符号の説明Explanation of symbols

４ 感光体
２０ 光学ハウジング
２１ 回転偏向手段（ポリゴンミラー）
２２ ｆθレンズ
２３ 長尺レンズ
２４ 第１ミラー
２５ 第２ミラー
２６ 第３ミラー 4 Photosensitive member 20 Optical housing 21 Rotating deflection means (polygon mirror)
22 fθ lens 23 long lens 24 first mirror 25 second mirror 26 third mirror

Claims (11)

単一の光学ハウジング内の略中央に備えられた唯一の回転偏向手段を中心として略対称となるように配置され、偶数個の感光体に対応する複数の走査光学系を備え、
各走査光学系の光学素子を介し、前記回転偏向手段を対称軸として左右に振り分けて、偶数個の感光体に同時に露光走査する対向走査型光走査装置であって、
各走査光学系が光学素子としてそれぞれ複数の折り返しミラーと副走査方向にパワーを持つ少なくとも１枚の長尺レンズとを有し、
前記回転偏向手段を中心に、互いに対称に配置される各走査光学系に対し、前記長尺レンズ以降の折り返しミラーの枚数を同数配置するとともに、長尺レンズが各々の走査面内において反転させて取り付けられていることを特徴とする光走査装置。 A plurality of scanning optical systems corresponding to an even number of photoconductors, arranged so as to be substantially symmetric with respect to a single rotational deflection means provided substantially at the center in a single optical housing;
An optical scanning device that scans an even number of photoconductors simultaneously by scanning the rotation deflecting means to the left and right through the optical elements of each scanning optical system;
Each scanning optical system has a plurality of folding mirrors and at least one long lens having power in the sub-scanning direction as optical elements,
For each scanning optical system arranged symmetrically with respect to the rotational deflection means, the same number of folding mirrors after the long lens are arranged, and the long lens is inverted in each scanning plane. An optical scanning device characterized by being attached. 単一の光学ハウジング内の略中央に備えられた唯一の回転偏向手段を中心として略対称となるように配置され、偶数個の感光体に対応する複数の走査光学系を備え、
各走査光学系の光学素子を介し、前記回転偏向手段を対称軸として左右に振り分けて、偶数個の感光体に同時に露光走査する対向走査型光走査装置であって、
各走査光学系が光学素子としてそれぞれ複数の折り返しミラーと副走査方向にパワーを持つ少なくとも１枚の長尺レンズとを有し、
前記回転偏向手段を中心に、左右の一方の方向において近い位置と遠い位置に配置される各走査光学系に対し、長尺レンズが各々の走査面内において反転させて取り付けられているとともに、前記長尺レンズ以降の折り返しミラーの枚数の差が、２Ｎ−１（Ｎは自然数）となるように配置することを特徴とする光走査装置。 A plurality of scanning optical systems corresponding to an even number of photoconductors, arranged so as to be substantially symmetric with respect to a single rotational deflection means provided substantially at the center in a single optical housing;
An optical scanning device that scans an even number of photoconductors simultaneously by scanning the rotation deflecting means to the left and right through the optical elements of each scanning optical system;
Each scanning optical system has a plurality of folding mirrors and at least one long lens having power in the sub-scanning direction as optical elements,
With respect to each scanning optical system arranged at a position close to and far from one of the left and right directions around the rotation deflection means, a long lens is mounted in an inverted manner in each scanning plane, and An optical scanning device, wherein the number of folding mirrors after the long lens is 2N-1 (N is a natural number). 請求項１または２に記載の光走査装置において、前記長尺レンズが樹脂材料による成形品であることを特徴とする光走査装置。   3. The optical scanning device according to claim 1, wherein the long lens is a molded product made of a resin material. 単一の光学ハウジング内の略中央に備えられた唯一の回転偏向手段を中心として略対称となるように配置され、偶数個の感光体に対応する複数の走査光学系を備え、
各走査光学系の光学素子を介し、前記回転偏向手段を対称軸として左右に振り分けて、偶数個の感光体に同時に露光走査する対向走査型光走査装置であって、
各走査光学系が光学素子としてそれぞれ複数の折り返しミラーと副走査方向にパワーを持つ少なくとも１枚の長尺レンズとを有し、
回転偏向手段を中心に各々対称配置された各折り返しミラー間の距離を、回転偏向手段における反射部を含めて、互いに等しくすることを特徴とする光走査装置。 A plurality of scanning optical systems corresponding to an even number of photoconductors, arranged so as to be substantially symmetric with respect to a single rotational deflection means provided substantially at the center in a single optical housing;
An optical scanning device that scans an even number of photoconductors simultaneously by scanning the rotation deflecting means to the left and right through the optical elements of each scanning optical system;
Each scanning optical system has a plurality of folding mirrors and at least one long lens having power in the sub-scanning direction as optical elements,
An optical scanning device characterized in that distances between the respective folding mirrors arranged symmetrically with respect to the rotational deflection means are made equal to each other including the reflection portion in the rotational deflection means. 請求項４に記載の光走査装置において、回転偏向手段を中心に対称配置された折り返しミラー面での光線の成す角を、少なくとも一対で互いに等しくしたことを特徴とする光走査装置。   5. The optical scanning device according to claim 4, wherein the angles formed by the light beams on the folding mirror surfaces arranged symmetrically with respect to the rotational deflection means are equal to each other in at least one pair. 請求項４または５に記載の光走査装置において、感光体表面上へ走査光を導く最終の折り返しミラーから感光体表面上までの距離を、各走査光学系に対し各々等しくしたことを特徴とする光走査装置。   6. The optical scanning device according to claim 4, wherein the distance from the final folding mirror that guides scanning light onto the surface of the photosensitive member to the surface of the photosensitive member is made equal for each scanning optical system. Optical scanning device. 単一の光学ハウジング内の略中央に備えられた唯一の回転偏向手段を中心として略対称となるように配置され、偶数個の感光体に対応する複数の走査光学系を備え、
各走査光学系の光学素子を介し、前記回転偏向手段を対称軸として左右に振り分けて、偶数個の感光体に同時に露光走査する対向走査型光走査装置であって、
各走査光学系が光学素子としてそれぞれ複数の折り返しミラーと副走査方向にパワーを持つ少なくとも１枚の長尺レンズとを有し、
前記回転偏向手段を中心に、左右方向における遠い位置に配置される各走査光学系に対し、すべての前記折り返しミラーを前記走査レンズの下流側に配置したことを特徴とする光走査装置。 A plurality of scanning optical systems corresponding to an even number of photoconductors, arranged so as to be substantially symmetric with respect to a single rotational deflection means provided substantially at the center in a single optical housing;
An optical scanning device that scans an even number of photoconductors simultaneously by scanning the rotation deflecting means to the left and right through the optical elements of each scanning optical system;
Each scanning optical system has a plurality of folding mirrors and at least one long lens having power in the sub-scanning direction as optical elements,
An optical scanning device characterized in that all the folding mirrors are arranged on the downstream side of the scanning lens with respect to each scanning optical system arranged at a far position in the left-right direction centering on the rotation deflection means. 請求項７に記載の光走査装置において、前記回転偏向手段を中心に、左右方向における近い位置に配置される各走査光学系は前記走査レンズの手前に1枚の前記折り返しミラーを配置したことを特徴とする光走査装置。   8. The optical scanning device according to claim 7, wherein each scanning optical system disposed at a position close in the left-right direction with the rotation deflecting unit as the center includes one folding mirror disposed in front of the scanning lens. An optical scanning device. 請求項８に記載の光走査装置において、前記走査レンズの手前に配置した折り返しミラーが他の折り返しミラーより短方向の幅が広いことを特徴とする光走査装置。   9. The optical scanning device according to claim 8, wherein the folding mirror disposed in front of the scanning lens is wider in the short direction than other folding mirrors. 請求項１、２，４〜９のいずれか一項に記載の光走査装置において、各々の走査光学系を形成する折り返しミラーの数を、何れの走査光学系でも同じ数とすることを特徴とする光走査装置。   10. The optical scanning device according to claim 1, wherein the number of folding mirrors forming each scanning optical system is the same in any scanning optical system. Optical scanning device. 前記請求項１〜１０のいずれか一項に記載の光走査装置を備えたことを特徴とする画像形成装置。












An image forming apparatus comprising the optical scanning device according to claim 1.












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